Fabrication of GaAs solar cells grown with InGaP layers by hydride vapor-phase epitaxy

摘要

The elevated manufacturing cost of highly efficient III-V multijunction devices limits them to space and high-concentration terrestrial applications. Hydride vapor-phase epitaxy (HVPE), in contrast to metal-organic vapor-phase epitaxy, can reduce the manufacturing costs due to the use of cheaper group III metal sources, capability to grow crystals under a low arsenic overpressure, and its low installation cost. In this study, we characterized the abruptness of the heterointerface between the InGaP and GaAs layers in GaAs solar cells grown by HVPE. InGaP passivation layers, such as the back-surface field (BSF) and window layers, were introduced in order to enhance the performance of the GaAs solar cells. Owing to the reduction of the surface recombination, the devices fabricated with the incorporated window layer showed a significant improvement in the short-wavelength range of the external quantum efficiency response, compared with that obtained for the unpassivated cells. This provided a cell efficiency improvement from 9.25 to 20.75%. However, the introduction of the BSF layer degrades the cell efficiency to 17.92%, owing to the formation of an anomalous interlayer at the GaAs-on-InGaP heterointerface. (C) 2018 The Japan Society of Applied Physics